Workers were evacuated from the Amtek Aluminium site in Freebornes Road, Witham as there were fears the fire would spread.

At 4.35am the fire had already penetrated the roof and walls of a building, measuring 100m x 50m, after breaking out in an extraction unit.

The site is made up of a number of smaller buildings all linked together, so crews had to work quickly to prevent the fire spreading. Attempts were made to shut down the electricity supply to the plant.

Firefighters surrounded the side wall of the building affected with hose reels and two main jets used.

An aerial platform was erected to pump water onto the roof with police called to direct traffic.

The incident commander reported that progress was being made by 5.30am as the fire in the extraction unit and side walls appeared to be out.

Crews have now located the fire in the extraction unit but its positioning means it is difficult to access.

A police spokesman said no-one had been hurt. Three appliances and an aerial ladder platform were initially called.

An investigation is to be carried out into the cause of the fire.

This is the 36th incident dealt with by Essex crews since members of the Fire Brigades Union went on strike at 9am yesterday over a dispute with the Government over pensions.